Add postinstall script

Author: alexcanessa

_postinstall.js

@@ -0,0 +1,22 @@
+const chalk = require('chalk');
+
+process.stdout.write(chalk.white(`
+                    ${chalk.yellow('| ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |')}
+                          ${chalk.blue(`🙏  Thanks for downloading ${chalk.green('gren')}`)}
+                    ${chalk.yellow('| ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |')}
+
+Before you start:
+
+    1. Generate a token with ${chalk.yellow('repo scope')} at this link: ${chalk.blue('https://github.com/settings/tokens/new')}
+    2. Run ${chalk.green('gren init')} to create a config file
+    3. Run ${chalk.green('gren help')} for more help or see ${chalk.blue('https://github-tools.github.io/github-release-notes/')}
+
+For any questions/issues, go here: ${chalk.blue('https://github.com/github-tools/github-release-notes/issues')}
+
+If you like ${chalk.green('gren')}, feel free to ⭐  it!
+
+
+${chalk.yellow('.:| ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |:.')}
+
+
+`));

package.json

@@ -9,7 +9,8 @@
         "coverage": "nyc --reporter=lcov --reporter=text mocha --compilers=js:babel-register",
         "options": "node tasks/_generate-options.js",
         "examples": "node tasks/_generate-examples.js",
-        "docs": "npm run options && npm run examples && node_modules/.bin/jsdoc -c .jsdoc.conf.json --verbose"
+        "docs": "npm run options && npm run examples && node_modules/.bin/jsdoc -c .jsdoc.conf.json --verbose",
+        "postinstall": "node ./_postinstall.js"
     },
     "repository": {
         "type": "git",